The specific aims of this core are the following: 1) To support collection and distribution of clinical samples and related clinical data for immune reconstitution studies described in the projects of this program project; 2) To provide rapid translation of novel therapeutic concepts developed in each project into multicenter phase II and III clinical trials; 3) To support to standardization of cell production, processing and transplantation technologies for multicenter clinical trials. This core is consortium of Harvard University, University of Minnesota, Los Angeles Children's Hospital, MD Anderson Cancer Center, and University of Perugia to perform clinical trials developed within the context of this grant. The core provides the infrastructure for translational implementation for the concepts developed in the projects and support rapid, definitive clinical evaluation of innovative strategies developed within this grant. The overall goal of this project is to achieve a greater understanding of the biologic basis for immunodeficiency after stem cell transplantation and to define treatment strategies that will improve both short-term and long-term immune functioning in hematopoietic transplant recipients. The core will coordinate and facilitate basic and clinical research on the biochemical and cellular bases of immune recovery after transplantation. This core is established to provide a multi-institutional clinical consortium to enable uniform, high-volume sample accrual and inter-institutional phase I/II clinical studies. This will allow this program project to research novel biologic and pharmacologic treatments aimed at improving functional status of patients after transplantation, and to look for clinical/laboratory relationships that ultimately may permit improved clinical evaluation of individual patients and/or assist in the evaluation of response to novel therapies. The core will develop and main!ain a sophisticated sample bank, and a secured on-line relational database that will allow for basic and clinical research studies on patients after transplantation, or on any one patient over time. The Clinical Core Steering Committee will relay information established in these studies in an advisory capacity to established cooperative groups in a way that may assist in triaging the relative merits of novel treatment strategies being considered for phase III testing.